Tag Archives: science

More laws of biology

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Four years ago I wrote a post asking whether there were any fundamental laws of biology that are sufficiently general to apply beyond the context of life on Earth [‘Laws of biology?‘ on January 16th, 2016].  I suggested Dollo’s law that diversity and complexity increases in evolutionary systems; the Hardy-Weinberg law about allele and genotype frequencies remaining constant from generation to generation; and the Michaelis-Menten law governing enzymatic reactions.  Recently, I came across a simpler statement of the laws of biology proposed by Edward O.Wilson.  He states that the first law of biology is all entities and processes of life are obedient to the laws of physics and chemistry; and the second law is all evolution, beyond minor random perturbations due to high mutation rates and random fluctuations in the number of competing genes, is due to natural selection.  It seems likely that these simpler laws will be universally applicable; however, until we find evidence of extra-terrestrial life, they will remain untestable in a universal context unlike the laws of physics.

Source:

Edward O. Wilson, Letters to a Young Scientist, Liveright Pub. Co., NY, 2013.

 

 

Inconvenient facts

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The latest UN Climate Change Conference in Madrid, which is holding its closing session as I am writing this post, does not appear to have reached any significant conclusions.  Unsurprisingly, vested interests have dominated and there is little agreement on a plan of action to slow down climate change or to mitigate its impact. However, perhaps there is progress because two recent polls imply that 75% of Americans believe humans cause climate change and roughly half say that urgent action is needed.  This is important because the USA has made the largest cumulative contribution to greenhouse gas emissions with 25% of total emissions, followed by the EU-28 at 22% and China at 13%, according to the Our World in Data website.  However, the need for urgent action is being undermined by suggestions that we cannot afford it, or that we will have better technology in the future that will make it easier to act.  However, much of the engineering technology that is needed to remove fossil fuels from our economy is already available.   Of course, the technology will be improved in the future but that is always true because we are continually making technological advances.  We could replace fossil fuels as the energy source for all of our electricity, buildings and heating (31%) and for most of our industry (21%) and transportation (14%) using the technology that is available today and this could eliminate about two-thirds of current global greenhouse gas emissions. The numbers in parentheses are the percentage contributions to global greenhouse gas emissions according to the IPCC. Of course, it would require a massive programme of infrastructure investment; however, if we are serious then the subsidies paid to the oil and gas industry could be redirected toward decarbonising our economies.  According to the IMF, that is approximately $5.2 trillion per year in subsidies, which is about the GDP of Japan.  The science of climate change is well-understood (see for example ‘What happens to emitted carbon‘ and ‘Carbon emissions and surface warming‘) and widely recognised; the engineering technology to mitigate both climate change and its impacts is largely understood and implementation-ready; however, most urgently, we need well-informed public debate about the economic changes required to decarbonise our society.

Sources:

Mark Maslin, The five corrupt pillars of climate change denial, The Conversation, November 28th, 2019.

United Nations Blog, The drive to a conclusion, December 13th, 2019.

Sandra Laville, Top oil firms spending millions lobbying to block climate change policies, says report, The Guardian, March 22nd 2019.

Footnote: The videos ‘What happens to emitted carbon‘ and ‘Carbon emissions and surface warming‘ are part of a series produced by my colleague, Professor Ric Williams at the University of Liverpool.  He has produced a third one: ‘Paris or Bust‘.

 

Citizens of the world

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Last week in Liverpool, we hosted a series of symposia for participants in a dual PhD programme involving the University of Liverpool and National Tsing Hua University, in Taiwan, that has been operating for nearly a decade.  On the first day, we brought together about dozen staff from each university, who had not met before, and asked them to present overviews of their research and explore possible collaborations using as a theme: UN Sustainable Development Goal No.11: Sustainable Cities and Communities.  The expertise of the group included biology, computer science, chemistry, economics, engineering, materials science and physics; so, we had wide-ranging discussions.  On the second and third day, we connected a classroom on each campus using a video conferencing system and the two dozen PhD students in the dual programme presented updates on their research from whichever campus they are currently resident.  Each student has a supervisor in each university and divides their time between the two universities exploiting the expertise and facilities in the two institutions.

The range of topics covered in the student presentations was probably even wider than on the first day; extending from deep neural networks, through nuclear reactor technology, battery design and three-dimensional cell culturing to policy impacts on households.  One student spoke about the beauty of mathematical equations she is working on that describe the propagation of waves in lattice structures; while, another told us about his investigation of the causes of declining fertility rates across the world.  Data from the UN DESA Population Division show that live births per woman in the Americas & Europe have already fallen below the 2.1 required to sustain the population, while it is projected to fall below this level in south-east Asia within the next five years and in the world by 2060.  This made me think that perhaps the Gaia principle, proposed by James Lovelock, is operating and that human population is self-regulating as it interacts with constraints imposed by the Earth though perhaps not in a fashion originally envisaged.

 

Size matters

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Most of us have a sub-conscious understanding of the forces that control the interaction of objects in the size scale in which we exist, i.e. from millimetres through to metres.  In this size scale gravitational and inertial forces dominate the interactions of bodies.  However, at the size scale that we cannot see, even when we use an optical microscope, the forces that the dominate the behaviour of objects interacting with one another are different.  There was a hint of this change in behaviour observed in our studies of the diffusion of nanoparticles [see ‘Slow moving nanoparticles‘ on December 13th, 2017], when we found that the movement of nanoparticles less than 100 nanometres in diameter was independent of their size.  Last month we published another article in one of the Nature journals, Scientific Reports, on ‘The influence of inter-particle forces on diffusion at the nanoscale‘, in which we have demonstrated by experiment that Van der Waals forces and electrostatic forces are the dominant forces at the nanoscale.  These forces control the diffusion of nanoparticles as well as surface adhesion, friction and colloid stability.  This finding is significant because the ionic strength of the medium in which the particles are moving will influence the strength of these forces and hence the behaviour of the nanopartices.  Since biological fluids contain ions, this will be important in understanding and predicting the behaviour of nanoparticles in biological applications where they might be used for drug delivery, or have a toxicological impact, depending on their composition.

Van der Waals forces are weak attractive forces between uncharged molecules that are distance dependent.  They are named after a Dutch physicist, Johannes Diderik van der Waals (1837-1923).  Electrostatic forces occur between charged particles or molecules and are usually repulsive with the result that van der Waals and electrostatic forces can balance each other, or not depending on the circumstances.

Sources:

Giorgi F, Coglitore D, Curran JM, Gilliland D, Macko P, Whelan M, Worth A & Patterson EA, The influence of inter-particle forces on diffusion at the nanoscale, Scientific Reports, 9:12689, 2019.

Coglitore D, Edwardson SP, Macko P, Patterson EA, Whelan MP, Transition from fractional to classical Stokes-Einstein behaviour in simple fluids, Royal Society Open Science, 4:170507, 2017. doi: 10.1098/rsos.170507.

Patterson EA & Whelan MP, Tracking nanoparticles in an optical microscope using caustics. Nanotechnology, 19 (10): 105502, 2009.

Image: from Giorgi et al 2019, figure 1 showing a photograph of a caustic (top) generated by a 50 nm gold nanoparticle in water taken with the optical microscope adjusted for Kohler illumination and closing the condenser field aperture to its minimum following method of Patterson and Whelan with its 2d random walk over a period of 3 seconds superimposed and a plot of the same walk (bottom).